My mom was just in the same predicament! She wanted to start walking to the train (over a mile walk), but because she carries her laptop everyday in a shoulder bag, it was too hard to carry. She wanted a backpack instead and ended up buying this:
http://www.coach.com/online/handbags...ACKPACK#102340
Maybe not the most fashionable, but she just wanted a nice backpack that didn't look soon...sportsy?
She's really happy with it so far. In my personal opinion, it seemed a bit small, but she says it can fit her shoes, laptop, wallet and lunch, so it seems to be working for her!
ETA: Wrong link--she got the nylon one, not leather one.